Explosion Rocks Central Paris, Injuring at Least 24 People

An explosion tore through an apartment building in central Paris on Wednesday, partly collapsing the structure and injuring at least 24 people, according to the French authorities.

The explosion, which occurred around 5 p.m. on Rue Saint-Jacques, in the Fifth Arrondissement of the French capital, projected rubble and glass into the street and started a fire that sent black smoke billowing into the sky.

Four of the people injured in the blast were in critical condition, according to the Paris police.

Laurent Nuñez, the Paris police prefect, told reporters more than 250 firefighters had deployed to the scene and were able to prevent the flames from spreading to neighboring buildings, which were nonetheless “seriously destabilized” and evacuated.

Mr. Nuñez said rescue workers were looking through the rubble late Wednesday for other potential victims. The Paris prosecutor’s office said at least two people were missing.

The cause of the explosion, which rattled the neighborhood with a loud boom, was not immediately clear. The prosecutor’s office said it had opened an investigation.

Some witnesses told French media that they had smelled a strong odor of gas shortly before the blast.

Laure Beccuau, the Paris prosecutor, told reporters at the scene that the blast appeared to have started in the building itself, which sits on the corner of a semicircular plaza, next to the ValdeGrâce church.

Ms. Beccuau said that investigators would try to determine whether the explosion was the result of individual negligence, noncompliance with building security rules or another cause. But the charges being considered by the prosecutor’s office — unintentional injuries — suggested foul play was not a leading theory.

Gilles Le Gendre, a French lawmaker who represents the area and who lives nearby, told the news channel BFMTV that there were several institutions in or near the building — including school administrative offices, a music and dance institute, and an American fashion school.

Videos and pictures on social media appeared to show the top of the building blown off and the street below strewn with debris.